Discharge device



s p 1941' J. E. BE'GGS ,25 7

DISCHARGE DEVICE Original Filed Feb. 9, 1940 Inventor" Jame'sBBe' s,-

. a His Attorney.

Patented Sept. 2, 1941 2,254,727 DISCHARGE DEVICE James E. Beggs, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Original application February 9, 1940, Serial No.

Divided and this application October 22, 1940, Serial No. 362,263

Claims.

This application is a continuation-in-part of my prior application Serial No. 266,558, filed April 7, 1939, and is a division of my prior application Serial No. 318,061, filed February 9, 1940. Both the aforesaid applications are assigned to the General Electric Company, a cor.- poration of New York. I

The invention claimed herein relates to enclosed electrical devices such as radio receiving tubes.

The invention has as its principal object the provision of improved gettering means for the removal of objectionable gases developed in the interior of a vacuum tube or the like during the final stages of tube manufacture. In this connection, a reactive substance having suitablegettering properties is located within a hollow tubulation which projects from and communicates with the main body of the tube envelope and which serves primarily as a guide for facilitating the engagement of the envelope with a cooperating socket. When gettering substance is flashed by the application of heat, the vaporized material is mainly confined to the interior of the tubulation so that its deposition on the electrodes and on other tube parts apt to be adversely affected by its presence is prevented. At the same time, its reaction with the gases desired to be removed from the tube is not materially hindered.

. The features which I desire to protect herein are pointed out with particularity in the apended claims. The invention itself, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the drawing, in which Fig. 1 is a view in partial section of a discharge device suitably embodying the invention; Fig. 2 is an exploded view showing the relationship of certain parts of the device of Fig. 1 prior to assembly thereof; Fig. 3 is an enlarged detail view of one feature of Fig. 1, and Figs. 4 and 5 respectively illustrate alternative variations of one aspect of the invention.

Referring particularly to Fig. 1 there is shown a discharge envelope comprising a seamless dome-like portion Hi and a' basing header ll, both of these parts being constituted of metal, for example, iron. Within the envelope there are provided a cathode IS, a control grid [4, a

screen grid [5, and an anode l6, these elements being arranged concentrically in the order named. (The anode, which is incompletely illustrated in the drawing, comprises a pair of parallel plate members which are joined at one edge by narrow metal strips, such as the strip which is indicated at I! in Fig. 1.) The various electrodes are respectively connected to lead-in conductors which are insulatingly sealed into the header I I by means of individual glass-tometal seals and of which the particular conductors shown are numbered l8 to 2| inclusive. Also, the header II is provided with an outwardly projecting protuberance or tubulation 23 which serves to assist in orienting the device as a whole in a cooperating socket and which provides electrostatic shielding between certain of the lead-in conductors.

The electrode elements above referred to are insulatingly supported by means of an appropriate framework. The particular arrangement shown for this purpose comprises a pair of insulating spacers indicated respectively at 25 and 26 in Fig. 2. These spacers are in turn supported and given a greater degree of rigidity by being positioned in metallic cup-like members 28 and 29. The'members 28 and 29 are both provided with transversely extending slots (such as that shown at 30 in Fig. 2), in order to permit the passage through the members of metal rods 3! for supporting the various grid electrodes and for providing terminal connections therefor. Corresponding terminal connections for the cathode are indicated at 32, and a connection tab for the anode is shown at 33. A flap 34 bent out of the member 28 permits the anode tab to pass through member 28 without danger of contact therewith. This flap and the other similarly numbered fiaps which are shown in the drawing 7 serve the additional function of shielding the anode tabs from the extremities of the control grid support rods and from the control grid connector 44.

In order to position the electrode assembly within the envelope, the supporting framework is provided with a part which is adapted to interfit with the hollow tubulation 23 of the header H. In the particular embodiment shown, this part is formed by the provision of wire uprights 36 and 31 which respectively extend through the insulators 25 and 26 so as to engage the same and which terminate at their lower ends in a common connecting portion 39 of generally hairpin shape. This connecting part is slightly tapered as indicated in Fig. 2 and is of such dimensions as to fit resiliently within the tubulation 23. It is furthermore provided with outwardly extending shoulders 40 which determine the degree of its penetration into the tubulation. Additional shoulders or offset portions, indicated at 4|, serve to facilitate the exact positioning of the uprights 36 and 31 with respect to the transverse members 28 and 29.

The arrangement above described affords a ready means of assembling the parts in their desired relationship prior to connecting the electrode terminals 3i, 32 and 33 to the various lead-in conductors. The procedure which is preferred in this connection involves first bringing the electrode assembly and the basing header 1 I, v

to the state of completion indicated in Fig. 2'. For reasons shortly to be explained, the surfaces of the header are preliminarily covered with a readily fusible metal or solder such as tin. Subsequent to the foregoing, the electrode framework and the basing header are'forced into. mu,- tual engagement so that the portion 39 of the framework is caused to slide into the tubulation 23. The resilience of the part 39 causes it to engage the interior walls of the tubulation and thus to hold the parts more or less rigidly in a temporary assembly. Thereafter, the various electrode terminals are connected to the lead-in conductors by appropriate wires or jumpers which are welded or otherwise secured in place evacuated chamber in accordancewith the-method described in my aforesaid prior application Serial No. 266,558. After the exhaust has proceeded to a desired point, the envelope is brought into abutting engagement with the header H,

as shown in Fig. 1, the assembly being suficientv ly heated at this time as a result of the exhaust operation to melt the fusible metal previously applied to the surfaces of the header. This operation results in joining the header to the main body of the envelope in hermetically sealed relation and assures the vacuum-tight character of the tube. Moreover, the fluxing of. the fusible metal at the contact surfaces which exist between the header and the parts 39and 40 will produce adhesion of these parts. Consequently, relative motion between them will thereafter be positively prevented and the assembly will remain rigidly fused during the subsequent handling and use of the tube.

According to the present invention, the tubulation 23 is provided internally with a gettering device, which, in the arrangement of Fig. l, is supported on the part 39. Such a device'may comprise, for example, a strip of metal ribbon 68 which is of channel-shaped cross-section so as to accommodate a quantity of an appropriate reactive substance 49. In this connection one may use a ribbon which is constituted of tantalum in combination with a substance which, in reaction with the tantalum, is adapted to evolve. a gas-absorbing element. Such a substance may comprise, for example, barium oxide, or a mixture of this material with strontium oxide.

The ribbon 48, which constitutes an electrical resistance element, is terminally connected at one end to the part 39 as by being welded thereto. At its other end it is connected to the leadin conductor 20 by means of a jumper connection 49 (see Fig. 1). In utilizing the getter itis only necessary to impress a sufficient voltage between the conductor 20 and the header to raise the ribbon to a temperature at which it is effective to cause reaction of the getter substances.

A particular advantage of the getter arrangement described in the foregoing lies in the possibility of using the resistance element 48 as a heating means for expediting the operation of joining the header H to the envelope shell Ill. To this end the ribbon is preferably made of sufficient heat-producing capacity so that it will serve to heat the header H substantially to the melting temperature of the solder applied thereto without becoming hot enough to cause reaction of the getter applied to the ribbon. I have found it advantageous in a particular case to use a resistance member which is capable of dissipating about seven watts without causing flashing of the getter substance. By this means it is possible to heat the header at a controlled rate so as to avoid cracking of the glass seals associated with the lead-in conductors. Additional heating of the envelope and header'may, of course, be produced by conventional induction methods. The enclosure of the gettering means within the tubulation 23 tends to avoid deposition of the getter material on the insulating parts of the electrode mounting structure. This advantage is onewhich maybe made use of even where the particular construction of Figs. 1 and 2 is not employed. For example, one alternative arrangement is shown in Fig.4 in which the getter ribbon is indicated at 48 and is shown to have its lower extremity connected directly to the bottom of a tubulation 23'.

In case it is desirable to take further precautions' to prevent escape of excess getter substance through the. opening of the tubulation, one may utilize an arrangement of-parts such as that shown in Fig. 5. In this casethe resistance ribbon, which is indicated at 48" is inclined to the axisof the tubulation 23" so that its lower surface is directed away from the opening of the tubulation. If the getter material is then applied exclusively to this surface, its vapors will have little tendency to escape into. the discharge space, but will, on the contrary, be projected mainly into the lower portion of the tubulation 23".

While the invention has been described by reference to particular structural embodiments thereof, it will be understood that numerous modifications thereof may be made by those skilled inthe art without departing from the invention. I, therefore, aim in the appended claims. to cover all such equivalent variations as come within the 'true spirit and scope of the foregoing disclosure.

What I claim as new. and desire to secure by Letters Patent of the United States is:

1. An enclosed electrical discharge device including' aterminal base having a hollow tubulation extending outwardly therefrom for the purpose of orienting the device in a cooperating socket, electrode structure within the envelope, wire uprights forming a framework for supporting the electrode structure, and resilient means forming an extension of said uprights for extending within and resiliently engaging the interior of the said. tubulation, said last-named meansyserving to maintain the said framework and electrode structure in a desired orientation with respect to the saidbase, and gettering means positioned in the said tubulation and supported by the, said resilient means. I

' 2. Anelectrical device comprising an envelope which encloses electrode structure, said envelope including a flattened wall portion, lead-in conductors extending through said wall portion for energizing the said electrode structure, a hollow tubular member projecting from the said wall portion and serving to facilitate orientation of the device in a cooperating socket, and gettering means positioned in said tubular member.

3. An electric discharge device comprising an envelope which encloses electrode structure, said envelope including a flattened wall portion, leadin conductors sealed through said wall portion for connection to the said electrode structure, a hollow tubular member projecting from the said wall portion and serving to facilitate orientation of the device in a cooperating socket, a gettering means positioned in said tubular member, and a resistance heater within said tubular member and forming a part of said gettering means.

4. An electric discharge device comprising an 20 least some of the conductors being connected to the said electrode structure, a hollow tubular member projecting outwardly from the header, and a gettering means within said tubular member, said means including a filamentary resistance heater electrically connected at its respective terminals to the header and to one of the said lead-in conductors.

5. An electric discharge device comprising an envelope which encloses electrode structure, a header closing one end of the envelope, lead-in conductors sealed through the header for energizing the electrode structure, a hollow tubular member projecting outwardly from the header, the space enclosed by said member communicating with the interior of the envelope through an opening in the header, a resistance heater within said tubular member and having at least certain surfaces thereof directed away from the said opening, and a getter substance applied to the said certain surfaces.

JAMES E. BEGGS. 

